Timed blink is a version of well known Arduino blink example that is shipped with the standard IDE, but is redesigned to use the Abstraction and timer library.
Example circuit for the code is exactly the same a blink, and if you use the inbuilt LED pin (which it does by default) then there’s no need to build any circuit whatsoever.
Instead of using
delay() calls to set the duration of the led flash, it uses the task
management library to schedule a task. In addition it uses the libraries IOAbstraction
facilities to switch the LED on and off. This means that the LED could be located on
a shift register or i2c IO device.